1. Technical Field
The present disclosure relates to a flat display device, and more particularly, to a gate driver which employs gate pulse modulation technology for improving an image quality, a driving method thereof, and a control circuit of a flat panel display device employing the gate driver.
2. Related Art
Recently, a variety of flat panel display devices have widely spread, and examples of the flat panel display devices may include a liquid crystal display (LCD) device, a light emitting diode (LED) display device, an organic LED (OLED) display device and the like.
Representatively, the LCD display device includes a liquid crystal panel and a driving circuit for driving the liquid crystal panel. The liquid crystal panel includes a plurality of gate lines and source lines intersecting each other, and pixels are defined at the respective intersections between the gate lines and the source lines. Each of the pixels is configured to switch a thin film transistor according to a gate pulse transmitted through a gate line, and represent an image according to a source signal transmitted through a source line and the thin film transistor.
The driving circuit includes a source driver for driving a source signal to a source line, a gate driver for driving a gate pulse to a gate line, and a timing controller for controlling the operations of the source driver and the gate driver. Furthermore, the driving circuit includes a voltage supply circuit configured to provide a voltage to the source driver, the gate driver, and the timing controller.
In general, when the thin film transistor of the LCD display device is turned off, a pixel voltage stored in each pixel may be changed according to a gate voltage variation of a parasitic capacitor included in the thin film transistor. More specifically, as soon as the thin film transistor is turned off, kick back may occur so that the charge stored in the pixel leaks through the parasitic capacitor of the thin film transistor. The kick-back may destabilize an output of a gate pulse. As a result, the image quality of a pixel driven by the gate pulse may be degraded.
In order to solve the above-described phenomenon, gate pulse modulation technology has been developed. The gate pulse modulation technology is to control turn-off of a thin film transistor using a modulated gate pulse.
The gate pulse modulation technology may generate power such that the power supply circuit has a gate pulse modulation waveform to modulate a gate pulse, and supply the generated power to gate drivers, and the gate drivers may output a modulated gate pulse using the power having a gate pulse modulation waveform. In this case, the power having a gate pulse modulation waveform is supplied to the gate driver through a high voltage power line for driving a gate.
The plurality of gate drivers are sequentially enabled, and sequentially output gate pulses to the respective gate lines of the liquid crystal panel.
When the power having a gate pulse modulation waveform is supplied to the gate drivers which are sequentially operated, the power supply circuit is configured to provide the power having a gate pulse modulation waveform to the entire gate drivers through the high voltage power line which is commonly coupled to the gate drivers.
That is, the power having a gate pulse modulation waveform is supplied regardless of the enable states of the gate drivers. As a result, the power may also be supplied to a gate driver which is not driven. Thus, the charge and discharge by the gate pulse modulation waveform are continuously performed in the high voltage power line for driving a gate and the capacitors included in the components of the entire gate drivers. As a result, unnecessary power consumption may occur, and the influence of electromagnetic waves may be caused by the power having a gate pulse modulation waveform.